1. Field of the Invention
This invention relates generally to communication systems, and, more particularly, to wireless communication systems.
2. Description of the Related Art
Service providers typically provide numerous voice and/or data services to subscribers using one or more wired and/or wireless communication systems. Exemplary services include cellular telephony, access to the Internet, gaming, broadcasting or multicasting of audio, video, and multimedia programming, and the like. Mobile subscriber units such as cell phones, personal data assistants, smart phones, pagers, text messaging devices, global positioning system (GPS) devices, network interface cards, notebook computers, and desktop computers may access the services provided by the communication systems over an air interface with one or more base stations. The services are provided according to established and/or negotiated policies and the service providers typically charge the end-users for the services that are provided. For example, a cellular telephone service provider may charge an end-user for each minute of airtime that is used during voice communications. The billing rate may be determined based on a negotiated policy indicating the quality of service to be provided to the end user. For another example, end-users may be charged for each byte of data that is transmitted and/or received by the mobile unit operated by the end-user. Consequently, wireless communication systems implement various charging and policy control architectures.
FIG. 1A conceptually illustrates a conventional policy and charging control architecture 100 as defined by the Third Generation Partnership Project (3GPP) in the 3GPP Technical Specification 23.203 in accordance with the WiMAX standards. The conventional policy and charging control architecture 100 includes one or more application functions (AF) 105 that offer applications that require dynamic policy and/or charging control. Each application function 105 can communicate with a policy control and charging rules function (PCRF) 110 over an Rx interface. The PCRF 110 provides network control rules regarding the service data flow detection, gating, and quality of service and/or flow-based charging towards a policy control and enforcement function (PCEF) 115 over a Gx/Ty interface. For example, the PCRF 110 can determine various policy and charging control (PCC) rules and transmit these rules to the PCEF 115. In some cases, the PCRF 110 determines the PCC rules based upon subscription information associated with a subscriber and stored in a subscription profile repository (SPR) 120.
The PCEF 115 resides in a gateway 125 that may be part of an access serving network (not shown in FIG. 1) of the wireless communication system. For example, the PCEF 115 is located in the GGSN for a GPRS network and the PDG for a WLAN. Alternatively, in a system that operates according to the Third Generation Partnership Project 2 (3GPP2) standards, the PCEF 115 could be located in a packet data serving node (PDSN) that is implemented in a gateway entity. The gateway 125 communicates with an online charging system 130 and/or an off-line charging system 135 over the interfaces Gy and Gz, respectively. The online charging system 130 may include a CAMEL SCP 140 and/or a charging control function 145. The online charging system 130 provides charging control (CC) rules to the PCEF 115. The PCEF 115, in conjunction with the online charging system 130 and/or the off-line charging system 135, implements service data flow detection, policy enforcement, and flow-based charging functionalities in accordance with the PCC/CC rules established by the PCRF 110. For example, the PCEF 115 may implement gate enforcement, quality of service enforcement, and charging control using the PCC/CC rules associated with subscribers to various services to ensure proper deployment and enforcement of quality of service policies and accurate charging.
FIG. 1B conceptually illustrates a conventional network 150 that supports mobility between a source radio access network 155(1) and a target radio access network 155(2). The WiMAX standards support access serving network and core serving network initiated handovers of mobile unit 160 that cause the PCEF 115 and in some cases simultaneously the Foreign Agent 165 to move from the source radio access network 155(1) to the target radio access network 155(2), as indicated by the arrow 170. In the illustrated embodiment, the mobile unit 160 is registered with a home network 175. The handoff procedures can be initiated by either the mobile unit 160 or an entity in the network, e.g., as part of a network resource optimization procedure. Delays and/or interruptions in communication between the PCRF 110, the PCEF 115, and/or the OCS 130 may result in the new serving PCEF 115 not receiving the PCC and/or CC rules that are needed to enforce the policies and/or charging rules associated with the subscriber and may result in inaccurate charging for any services received by the subscriber.